Composite metal



Patented May'1 2,193l

UNITED STATES PATENT OFFICE HERMAINN VON FOBSTER, OF NIEDERURSEL, NEARFRANKFORT-ON-THE-MAIN, AND

EH11 LAY, OF ESCHERSHEDH, NEAR FRANKFORT-ON-THE-MATN, GERMANYQASSIGN-OBS T0 METALLGESELLSCHAFT AKTIENGESELLSCHAIT, OF FRANKFORT-ON-THEIilZAIN, GERMANY, A. CORPORATION OF GERMANY 7 COMPOSITE METAL E0Drawing. Application filed September-11, 1929, Serial No. 391,982, andin Germany April 20, 1927. v

This invention relates to composite metals, produced by welding coatingmetals on to IIOIl cores, preferably by the casting-on process.

A great variety of coating metals have alunsuitable, since in such casethe hot shap- I ing treatment rendered the workpiece useless although,in themselves, brass alloys and particularly such alloys as contain 55-60% of copper, can be worked by hot rolling. By maintaining suitableconditions, it

I is also possible to hot roll and forge grades of brass with a stillhigher content of copper. A small addition of iron or manganeseincreases the workability of the material at red heat, whereas even aslittle as 0.5% of lead impairs the suitability forrolling.

In hot rolling composite metals, however,- the coating metal must complywith requirements' which are entirely different from those in caseswhere the coating metal is to be worked by itself. F orinstance, in thecase of composite metals the coating metal must be able not only tostand the shaping treatment perfectly, but also there must be noloosening of the welded union between it and the core metal. Since, inaddition, the iron core is generally substantially harder than the brassalloy, the brass alloy would sustain an incomparably greater stress atthe weld surface, in rolling, than if worked separately. It wastherefore impossible to ascertain in advance whether a brass alloy whichcould be satisfactorily hot rolled, could also be used as coating metalfor a composite metal to be hot rolled, and, as a matter of fact, it hasbeen found that brass alloys containing less than of copper (which, asis well known, are the most suitable for hot rolling) cannot be employedfor this purpose.

from the iron core outwards. nor the maximum fineness of grain is ob-'The present invention contemplates the production of a composite metalsuitable for hot rolling, by welding copper-zinc alloys containing morethan 60% vof copper, as a coating, on to an iron core. found thatbimetallic wire can be successfully made from rolled bars, produced bycasting brass around iron in ots, provided the brass be made, not fromthe commercial grades of zinc hitherto used, but from zinc containingless than 0.01% of lead. The total lead content of the alloy should notexceed 0.01%. In addition 0.0 5l% of manganese may be incorporated insuch brass.

Ingots of this kind can be rolled down into wire by the usual processwithout diffi- .culty. The capacity for rolling can be further improvedby incorporating in the brass an amount of iron exceeding that whichalways dissolves in the coating metal in the casting-on process andwhich is adequate for a satisfactory welded union. The dissolving ofiron in the cast-on metal should rather proceed to such an extent asalso to affect the texture of the cast-on metal. This result isadvantageously attained by maintaining, for a certain time during theWelding process or that of casting on to the iron core, a temperaturewhich is favourable to the dissolution of the iron in the cast-ontermined by the amount of core metal it It has" been is desired totransfer into the coating metal.

The iron. may, of course, also be introduced in other ways;nevertheless, the procedure set forthailords the particularadvantagethat the iron content in the brass coating, within certainlimits progressively decreases In this mantained at the place where thecomposite metal is subjected to the maximum stress during hot rolling,whilst the outer zones, which have taken up the smallest amount of iron,retain the original properties of the brass,'such as colour, ductility,and the like.

The hereindescribed process enables products which are completely freefrom defects, and similar to those obtained in the manufacture of ironand copper "wires to be produced.

We claim: 7 l. A composite metal produced by welding a coating ofcopper-zinc alloy onto an iron core by the casting-on process, characterizedin that the copper-zinc alloy contains over 60% of copper andless than 0.01% of lead. V 10 2; Composite metal as set forth in claim 1in which 0.051% of manganese is alloyed with the copper-zinc alloy.

3. Composite metal as set forth in claim 1, in which copper-zinc alloycontains a small proportion of iron.

4. Composite metal as set forth in claim 1, in which the copper-zincalloy contains 0.051% of manganese and a small amount of iron. Intestimony whereof we afix our signa tures.

HERMANN v. FORSTER. DR. EMIL LAY.

